Statistical Analysis of the Factors influencing the In Situ U-Value of Walls
Received: 13 January 2024 | Revised: 2 February 2024 | Accepted: 7 February 2024 | Online: 16 February 2024
Corresponding author: Smita Rashmi
Abstract
Building thermal performance testing requires in situ measurement techniques that are well supported and validated by simulation with statistics to improve the accuracy of the results. Local on-site performance of building components is different from the theoretical one, influenced by factors affecting the building's thermal conditions. The current paper reviews the factors influencing the measured U-value results in the heat flux method based on quantitative findings of other studies through regression and correlation statistics. The findings regarding the current status of knowledge are limited to in situ methods without detailed insights of response time, sensitivity analysis, and thermal boundary conditions in the local context. Regression analysis between wall characteristics, time duration, temperature difference, and the measured U-value shows a very strong and statistically significant impact of these variables on the accuracy of the measured U-value of low transmittance walls. The R2 value indicates that three variables can collectively explain 91% of the variance in the measured U-value. There is a linear correlation between the wall characteristics and the measured U-value and a non-linear correlation between the time duration, temperature difference, and the measured U-value. Future work will focus on developing a measurement framework that considers time-dependent variables, dynamic weather, and uncertainty with high accuracy for different boundary conditions.
Keywords:
thermal measurement, in situ measurement, U-value, heat flux method, regression analysisDownloads
References
J. Kuhle, "Comment: ‘If you can’t measure it, you can’t improve it’ (Lord Kelvin)," Neurology, vol. 87, no. 13, pp. 1335–1335, Sep. 2016.
L. Sawyer, P. de Wilde, and S. Turpin‐Brooks, "Energy performance and occupancy satisfaction: A comparison of two closely related buildings," Facilities, vol. 26, no. 13/14, pp. 542–551, Jan. 2008.
K. W. Tham, P. Wargocki, and Y. F. Tan, "Indoor environmental quality, occupant perception, prevalence of sick building syndrome symptoms, and sick leave in a Green Mark Platinum-rated versus a non-Green Mark-rated building: A case study," Science and Technology for the Built Environment, vol. 21, no. 1, pp. 35–44, Jan. 2015.
B. Bordass, R. Cohen, M. Standeven, and A. Leaman, "Assessing building performance in use 2: technical performance of the Probe buildings," Building Research & Information, vol. 29, no. 2, pp. 103–113, Mar. 2001.
A. M. Nii, A. Emmanuel, and A. Joshua, "Developing a Building Energy Efficiency Assessment Tool for Office Buildings in Ghana: Delphic Consultation Approach," Energy Procedia, vol. 111, pp. 629–638, Mar. 2017.
A. S. Mahmoud, "Overview of Green Roof Technology as a Prospective Energy Preservation Technique in Arid Regions," Engineering, Technology & Applied Science Research, vol. 12, no. 4, pp. 8982–8989, Aug. 2022.
T. Scussiato, W. H. Ito, J. Ramis, and P. I. B. de Queiroz, "A Numerical Model for Heat and Moisture Transfer in Porous Media of Building Envelopes," Engineering, Technology & Applied Science Research, vol. 12, no. 5, pp. 9239–9246, Oct. 2022.
T. Chati, K. Rahmani, T. T. Naas, and A. Rouibah, "Moist Air Flow Analysis in an Open Enclosure. Part A: Parametric Study," Engineering, Technology & Applied Science Research, vol. 11, no. 5, pp. 7571–7577, Oct. 2021.
G. Desogus, S. Mura, and R. Ricciu, "Comparing different approaches to in situ measurement of building components thermal resistance," Energy and Buildings, vol. 43, no. 10, pp. 2613–2620, Oct. 2011.
A. Ahmad, M. Maslehuddin, and L. M. Al-Hadhrami, "In situ measurement of thermal transmittance and thermal resistance of hollow reinforced precast concrete walls," Energy and Buildings, vol. 84, pp. 132–141, Dec. 2014.
L. Evangelisti, C. Guattari, P. Gori, and R. D. L. Vollaro, "In Situ Thermal Transmittance Measurements for Investigating Differences between Wall Models and Actual Building Performance," Sustainability, vol. 7, no. 8, pp. 10388–10398, Aug. 2015.
L. Evangelisti, A. Scorza, R. De Lieto Vollaro, and S. A. Sciuto, "Comparison between Heat Flow Meter (HFM) and Thermometric (THM) Method for Building Wall Thermal Characterization: Latest Advances and Critical Review," Sustainability, vol. 14, no. 2, Jan. 2022, Art. no. 693.
R. Albatici, A. M. Tonelli, and M. Chiogna, "A comprehensive experimental approach for the validation of quantitative infrared thermography in the evaluation of building thermal transmittance," Applied Energy, vol. 141, pp. 218–228, Mar. 2015.
L. Zalewski, S. Lassue, D. Rousse, and K. Boukhalfa, "Experimental and numerical characterization of thermal bridges in prefabricated building walls," Energy Conversion and Management, vol. 51, no. 12, pp. 2869–2877, Dec. 2010.
H. Nowak and Ł. Nowak, "Non-Destructive Possibilities of Thermal Performance Evaluation of the External Walls," Materials, vol. 14, no. 23, Jan. 2021, Art. no. 7438.
G. P. Mitalas and D. G. Stephenson, "Room thermal response factors," ASHRAE Transactions, vol. 73, Jan. 1967, [Online]. Available: https://www.osti.gov/biblio/5069807.
A. Rasooli, "In-Situ Determination of Buildings’ Thermo- Physical Characteristics: Method Development, Experimentation, and Computation," A+BE | Architecture and the Built Environment, no. 07, pp. 1–228, Jun. 2020.
B. Tejedor, M. Casals, M. Gangolells, and X. Roca, "Quantitative internal infrared thermography for determining in-situ thermal behaviour of façades," Energy and Buildings, vol. 151, pp. 187–197, Sep. 2017.
A. François, L. Ibos, V. Feuillet, and J. Meulemans, "Novel in situ measurement methods of the total heat transfer coefficient on building walls," Energy and Buildings, vol. 219, Jul. 2020, Art. no. 110004.
K. Gaspar, M. Casals, and M. Gangolells, "In situ measurement of façades with a low U-value: Avoiding deviations," Energy and Buildings, vol. 170, pp. 61–73, Jul. 2018.
K. Gaspar, M. Casals, and M. Gangolells, "Review of criteria for determining HFM minimum test duration," Energy and Buildings, vol. 176, pp. 360–370, Oct. 2018.
B. Tejedor, M. Casals, and M. Gangolells, "Assessing the influence of operating conditions and thermophysical properties on the accuracy of in-situ measured U-values using quantitative internal infrared thermography," Energy and Buildings, vol. 171, pp. 64–75, Jul. 2018.
X. Meng, T. Luo, Y. Gao, L. Zhang, Q. Shen, and E. Long, "A new simple method to measure wall thermal transmittance in situ and its adaptability analysis," Applied Thermal Engineering, vol. 122, pp. 747–757, Jul. 2017.
B. Tejedor, M. Casals, M. Macarulla, and A. Giretti, "U-value time series analyses: Evaluating the feasibility of in-situ short-lasting IRT tests for heavy multi-leaf walls," Building and Environment, vol. 159, Jul. 2019, Art. no. 106123.
A. Rodler, S. Guernouti, M. Musy, and J. Bouyer, "Thermal behaviour of a building in its environment: Modelling, experimentation, and comparison," Energy and Buildings, vol. 168, pp. 19–34, Jun. 2018.
A. Rasooli, L. Itard, and C. I. Ferreira, "A response factor-based method for the rapid in-situ determination of wall’s thermal resistance in existing buildings," Energy and Buildings, vol. 119, pp. 51–61, May 2016.
Downloads
How to Cite
License
Copyright (c) 2024 Smita Rashmi, Ravish Kumar
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors who publish with this journal agree to the following terms:
- Authors retain the copyright and grant the journal the right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) after its publication in ETASR with an acknowledgement of its initial publication in this journal.
